Humans with hippocampal damage, including those with Alzheimer's disease, suffer severe amnesia. However, although this fact makes it clear that the hippocampal system is critical in the creation of memories, it is not known how the different components of the hippocampal system interact during memory formation. The proposed work attempts to separately examine the roles of different hippocampal components in both the formation of new memories and the consolidation of old memories. These experiments involve the assessment of learning and memory in rodents following selective damage to subareas within this brain system. The hippocampal areas examined will be the hippocampal formation, the subiculum, the entorhinal cortex, and the perirhinal cortex. In addition, the functions of dorsal versus ventral hippocampus will also be examined. A small battery of tasks which are posited to be dependent on the different hippocampal components will be used to assess learning and memory.